I found reading Julia Chang's information, at http://www.sensiblehealth.com to be very helpful. I have just ordered her tincture, chinese bitters, which is supposed to loosen the bile stuck in the liver. After doing my first flush, I do believe that for me this may be crucial, since the stones I got out stuck to high heaven. I figured they wouldn't smell so bad if they weren't stuck in bile (just my guess, anyway), so her approach makes sense to me.
Also I have heard, and i didn't do it this time, that drinking apple juice for 6 days prior to the flush, as andreas says, helps... did you do this?